```
public interface ImmutableActiveFlowStackI
```
The stack of active flows. This is stack of stacks, that is, a two-dimensional structure. For each active normal flow a substack entry exists in the main stack, and the normal flow is the bottom element of that substack. It is the only normal flow in that substack. The substack can also contain zero or more subflows on top of the normal flow.

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Iterable<? extends ImmutableActiveFlowI>`	`asFlatIterable()`	Returns an `Iterable` over all flows in the stack.
`ImmutableActiveFlowI`	`getMain(int _iIndex)`	Returns the normal flow at the given index.
`ImmutableActiveFlowI`	`getSub(int _iIndex)`	Returns the flow at the given index of the topmost substack.
`List<? extends ImmutableActiveFlowI>`	`getSubStack(int _index)`	Returns the substack at the given index.
`boolean`	`isEmpty()`	Returns whether the stack is completely empty.
`boolean`	`isSub()`	Returns whether the topmost flow (as returned by `peekSub()`) is a subflow.
`ImmutableActiveFlowI`	`peekMain()`	Returns the topmost normal flow (regardless whether subflows exist on top of it).
`ImmutableActiveFlowI`	`peekSub()`	Returns the topmost flow (can be a normal flow or a subflow).
`int`	`size()`	Returns the number of normal flows on the stack.
`int`	`sizeFlat()`	Returns the total number of flows in the stack.
`int`	`sizeSub()`	Returns the size of the topmost substack.

Interface ImmutableActiveFlowStackI